The researchers, from the Randall Division of Cell and Molecular Biophysics, King's College London, are working on a molecule vital to a chicken's immune system, which represents the evolutionary ancestor of the human antibodies that cause allergic reactions.

Crucially, they have discovered that the chicken molecule behaves quite differently from its human counterpart, which throws light on the origin and cause of allergic reactions in humans and gives hope for new strategies for treatment.

Researcher, Dr Alex Taylor said: "This molecule is like a living fossil - finding out that it has an ancient past is like turning up a coelacanth in your garden pond. By studying this molecule, we can track the evolution of allergic reactions back to at least 160 million years ago and by looking at the differences between the ancient and the modern antibodies we can begin to understand how to design better drugs to stop allergic reactions in their tracks."

The chicken molecule, an antibody called IgY, looks remarkably similar to the human antibody IgE. IgE is known to be involved in allergic reactions and humans also have a counterpart antibody called IgG that helps to destroy invading viruses and bacteria.

Scientists know that both IgE and IgG were present in mammals around 160 million years ago because the corresponding genes are found in the recently published platypus genome. However, in chickens there is no equivalent to IgG and so IgY performs both functions.